In the past grant period, we have shown that HSV-2 specific CD8+ T cells reside and persist at the dermal-epidermal junction (DEJ) contiguous to the sensory nerve termini innervating the basal keratinocytes of the genital skin. Using laser capture microdissection we have isolated single CD8+ DEJ T cells in situ and interrogating these cells with transcriptional arrays and quantitative RT PCR assays. Our data indicates these cells express a wide variety of cytolytic and antiviral cytokines, as well as a unique homodimeric ?? chain signature. We have also developed rigorous and specific sampling methods to precisely pinpoint the sites of HSV-2 reactivation in the genitalia in time and space. Our preliminary data have shown wide differences in the number of CD8+ DEJ T cells in areas of genital skin. We now propose to apply these and other advanced methodologies to understand the immune surveillance mechanism of HSV-2 specific CD8+ T cells. Specifically, in Aim 1 we will probe the relationship between immunosurveillance and duration, severity, and frequency of HSV-2 reactivation. We hypothesize that the number of CD8+ T cells and/or their levels of expression of cytolytic and antiviral cytokines/chemokines will be inversely correlated with frequency of HSV-2 reactivation. Areas in which DEJ CD8+ T cells are in low numbers or express low functional activity will have a greater likelihood of reactivation than areas which are populated with high CD8+ T cells at the DEJ. We will also explore the relationships between clonal diversity and reactivation. Aim 2 is directed at defining host-viral interactions among HIV+ persons. We hypothesize that HIV+ persons will exhibit altered quantitative and functional differences in immune surveillance and that these differences will be reflected in poorer containment of HSV-2. The comparisons between HIV+/HSV-2+ and HIV-/HSV-2+ persons will provide further evidence of the importance of CD8+ T cells at the DEJ in immune surveillance and corroborate the mechanistic functions define in S.A. 1. PUBLIC HEALTH RELEVANCE: This proposal aims to understand the mechanism by which host immune cells, specifically resident mucosal CD8+ T cells, contain herpes simplex virus-2 (HSV-2) reactivation at the source of their release from neuronal termini into basal keratinocytes of the genital skin/mucosa. Using laser capture microdissection and transcriptional arrays, we have shown that HSV-2 specific CD8+ T cells persist at the dermal-epidermal junction and that these cells express several cytolytic and antiviral cytokines. We now aim to further study the immune surveillance function of these cells and how they contain viral reactivation, a key concept that will lay the groundwork for better design and development of HSV-2 vaccines.